Pen set



FIG. 1 is a perspective view of a pen set showing my new design;

FIG. 2 is a front elevational view thereof, the side opposite being substantially a mirror image;

FIG. 3 is a top plan view thereof; and

FIG. 4 is a side elevational view thereof, the side opposite being substantially a mirror image. 

The ornamental design for a pen set, as shown and described. 